Hi Andy,

re:
> Michael - how do I tell the sweep to make sure the surfaces all end on the plane for the end circle?
> It's sweep that created those misalignments.

You've got to make the rail curve to be more accurate - currently some of your rail curves have an end tangent that is out of line with the world z axis (see above screenshot). So that introduces a kind of slant into the sweep.

- Michael